The present invention relates to a separator or cage for ball bearings, the separator including pockets that are approximately adapted to the size of the ball in the pocket, and particularly pocket surfaces with a plurality of cylindrical regions.
A separator of this type is known from Federal Republic of Germany Published Application OS 36 40 633. In that case, the pocket sections have flat zones so that contact with the balls can take place only in those zones. The conditions of the contacts between the separator pockets and the balls are improved because small area contact zones are present only at given points. The narrowing slots which are circumferentially alongside the small area contact zones build up a hydrodynamic lubricating film which can support a smaller load since the load bearing lubricating wedges are relatively small. The pocket sections alongside the flat zones are equidistantly spaced from the balls and therefore do not form bearing surfaces. There are frequent contacts between the balls and the separator. This, in turn, substantially increases both the amount of noise developed and the friction. For instance, when such ball bearings are used in fixed disk spindles, the increase is to such an extent that errors can occur in the writing and reading of the data.